This type of vehicle has a guide device on each of its road axles carrying one or more followers that follow the guide rail and orient the axle using the guide device.
There are for instance known guide devices comprising a single or double arm connected to the axle by a shaft and extending toward the guide rail, with, at the free end, a pair of guide rollers angled in a V, each traveling along an opposing path on the central guide rail.
Now, this type of vehicle usually travels on a dedicated track and alternates in both directions of travel with no U-turn maneuvers. Therefore, it must be possible to guide the vehicle in both directions of travel.
In this case the guide device previously described needs to be duplicated on each axle with a similar device oriented in the other direction, thus forming a bidirectional guide system. Each of the guide devices on the bidirectional guide system is used alternately depending upon the direction in which the vehicle is traveling.
In order to safely and reliably guide the vehicle, the active guide device must be rigidly connected to the corresponding axle for the purpose of transmitting changes in direction to it and consequently orienting it correctly.
If the two opposing guide devices on the bidirectional guide system are rigid in order to orient the axle in any direction the vehicle is traveling, the result is a hyperstatic system with considerable lateral stress impacting it, particularly if there are curves along the route, if there are cross winds, or if skidding on slippery terrain. Consequently, the guide system must be designed to withstand these lateral stresses.
But, the tires on the vehicle are able to absorb this lateral stress without any problems or modifications. Actually, in non-guided vehicles, it is primarily the tires that are subjected to this stress. When turning, for example, they are subjected to lateral acceleration that temporarily deforms their sides.